In cellular wheel sluices with a horizontally disposed cellular wheel, the shafts are in principle rotatably supported in the side covers disposed laterally on the housing.
The spacing between the cellular wheel bodies, which can be deformed only slightly, and the ball bearing is dependent on the selected shaft seal, radial packing ring, slide ring seal or stuffing box seal and determines the sagging of the cellular wheel shaft stub, when differential pressure is applied to the inlet or outlet of the cellular wheel sluice.
For rotating the cellular wheel in the housing, a gap is necessary, which is composed of the following criteria:
Taking into account
the sagging PA1 the production tolerance PA1 the effective temperature PA1 the necessary margin of safety in all possible loading situations.
Assuming a standard gap of 0.10 to 0.25 mm, then depending on the cellular wheel diameter it will be appreciated that producing cellular wheel sluices for dense-phase feeding presents difficulties, especially given the pronounced trend toward 6-bar feeding systems, which until now have been used only for pressure vessels.
On the one hand, the bearing should be embodied as simply as possible, but on the other it must meet the demand for increasing loads.
In terms of process technology, changing the location of the cellular wheel relative to the pivot axis in the housing leads to the characteristic air leakage curves under rising pressure and when a lateral seal is used it takes considerable effort to protect the seal from the bending motion with the goal of achieving a desirably long service life.
German Patent DE 39 40 667 describes sealing struts that are guided by rollers on the housing, in order to reduce wear of the sealing struts from the bending motion and thus to relieve them from the pressure of the struts in the bending direction toward the housing.
In practice, this is feasible only for bulk goods with particles sizes of 2 .times.S (where S =the gap), because the support roller would simply roll over a smaller particle size. This cancels out the seal and renders it inoperative.